Polyimides are polymers formed from imide monomers, and are known having been produced since the 1950s. A number of methods are known for making polyimides, and these include reacting dianhydride and diamine, or reacting dianhydride and diisocyanate. The former is the most common method.
The basic structure of imide monomer is shown below.

On polymerisation, the resulting product is a polyimide which typically takes one of two forms. The first of these is a linear structure where the atoms of the imide group are part of a linear chain, the second of these structures is a heterocyclic structure where the imide group is part of a cyclic unit in the polymer chain.

Typically, most commercial polyimides are aromatic heterocyclic polyimides, with examples includes those sold under the Ultem brand from Sabic Innovative Plastics and those sold under the Kapton from DuPont. These types of polyimides are known for their mechanical and thermal properties which derive from intermolecular forces between the polymer chains, and they are often used in place of metals and glass in many high performance applications in the electronics, automotive, and aerospace industries.
Self-healing is a novel technology which is desired in places that are difficult to access for repairs, applications where reliability and safety are key, and in long lasting or aesthetic applications (e.g. electronics, transportation, aerospace etc.). Existing polyimides polymers are not know to have such properties.